Comparison between AlGaN surfaces etched by carbon tetrafluoride and argon plasmas: Effect of the fluorine impurities incorporated in the surface

Kawakami, Retsuo; Niibe, Masahito; Nakano, Yoshitaka; Shirahama, Tatsuo; Hirai, Shodai; Mukai, Takashi

doi:10.1016/j.vacuum.2015.06.002

Cited by 12 publications

(19 citation statements)

References 41 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, the main species of CF 4 plasma should be CF + 3 ions and F radicals [14]. The formation of non-volatile fluorine compounds of Al(OH) x F y and GaF x has previously been suggested for AlGaN surfaces etched with CF 4 plasma even for a short time [11]. Thus, the suppression of the selective etching of N would have been caused by the formation of these fluorine compounds protecting the AlGaN surface.…”

Section: Resultsmentioning

confidence: 98%

“…The etch depth of the AlGaN surface etched for a processing-time of 100 min was about 60 nm regardless of the gas species and gas pressure [11]. Figure 2 shows SEM images of the AlGaN surface etched for a processing-time of 100 min.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, we have etched AlGaN film with CF 4 and Ar plasmas, and analyzed the treated surface with various methods. Although we have reported part of the study, such as the resulting variation in surface shape, elsewhere [11], a microscopic understanding of the etching damage is not sufficient. The damage caused by CF 4 plasma etching is more easily understood by comparing the etching damage caused by both CF 4 and Ar plasmas using the same etching device.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Hirai

Niibe

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

Self Cite

View full text Add to dashboard Cite

To understand the surface damage of AlGaN film caused by plasma etching in detail, we etched AlGaN film with CF4 and Ar plasmas. The intensity of ultraviolet (UV) light emitted from the CF4 plasma was very weak at each gas pressure investigated. However, in the case of Ar, a certain degree of UV intensity was observed at gas pressures between 50 and 100 mTorr. The surface etched with the CF4 plasma was as smooth as that of the as-grown film. In the case of Ar, surface roughening occurred at gas pressures between 50 and 100 mTorr. The Al/N and Ga/N ratios of the AlGaN surface etched with Ar plasma increased more significantly than those of the surface etched CF4 plasma, as determined by X-ray photoelectron spectroscopy (XPS). The peak shape of the near-edge X-ray absorption fine structure (NEXAFS) spectra in the N-K absorption edge was broadened by the plasma etching with increasing processing-time. The broadening observed in the case of Ar etching was greater than that during CF4 plasma etching. The observed changes in the surface morphology and crystalline structure of the AlGaN are considered to be caused by the synergistic effect of UV light irradiation from the plasma and ion bombardment of the sample surface. The changes in surface composition, surface roughening, and the disordering of the crystalline structure were found to occur within a shallow region from the surface, and did not occur in deeper regions of the sample. F atoms (ions) were found to penetrate the surface to a depth of about 10 nm in the AlGaN etched with CF4 plasma.

show abstract

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Hirai

Niibe

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover, even N 2 plasma irradiation can achieve the normally‐off operation, which suggests that another origin is related to the achievement of normally‐off operation. On the other hand, plasma irradiation with impact of ultraviolet (UV) photons generally causes damage on the AlGaN surface such as a compositional change in the surface . The plasma‐induced damage results in degradation of electrical characteristics such as a decrease in mobility and concentration of the 2DEG channel .…”

Section: Introductionmentioning

confidence: 99%

“…We previously discussed the effect of fluorine‐related impurities incorporated into Al 0.24 Ga 0.76 N thin film surface by CF 4 plasma irradiation by comparing it with the effect of Ar plasma irradiation, in terms of the impact of near‐UV photons emitted from the plasma . This comparison concluded that the incorporation of fluorine atoms, which bond with cation vacancies such as gallium and aluminum vacancies introduced into the surface by CF 4 plasma, reduced the degree of nitrogen deficiency and formed a smooth surface in the absence of the emitted near‐UV photons.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of N₂ and O₂ Plasma‐Induced Damages on AlGaN Thin Film Surfaces

Kawakami

Niibe

Nakano

et al. 2017

Physica Status Solidi (a)

Self Cite

View full text Add to dashboard Cite

A fundamental understanding of N 2 and O 2 plasma-induced damage on AlGaN surface is needed in order not to severely degrade electrical characteristics and in order to intelligently achieve the normally-off operation of AlGaN/GaN-based electronic devices. A difference between the damage characteristics of Al 0.24 Ga 0.76 N thin film surfaces irradiated with N 2 and O 2 plasmas is reported, from the perspective of impact of ultraviolet (UV) photons emitted from the plasmas. With the lengthening irradiation time, N 2 plasma irradiation introduced a large degree of nitrogen deficiency under the influence of near-UV photons with energies of 3.68 and 3.93 eV larger than the AlGaN band-gap energy, compared to O 2 plasma irradiation without the emission of near-UV photons. In a short irradiation time, O 2 plasma irradiation introduced a larger degree of nitrogen deficiency. With increasing gas pressure, O 2 plasma-induced damage on the surface was more enhanced than N 2 plasma-induced damage. The degree of aluminum deficiency was more enhanced than that of gallium deficiency, the amount of oxides incorporated into the surface was suppressed, and the etch-pit density comparable to the dislocation density was introduced on the surface. These findings can be attributed to the impacts of vacuum ultraviolet photons and energetic O þ ions from the O 2 plasma.

show abstract

Plasma treatment of polymethyl methacrylate to improve surface hydrophilicity and antifouling performance

Sui

Shen

et al. 2020

Polymer Engineering & Sci

View full text Add to dashboard Cite

Surface modification of polymethyl methacrylate (PMMA) by O2/CF4 plasma is investigated to improve hydrophilicity and antifouling performance of PMMA. The PMMA surface before and after treatment is characterized by atomic force microscopy, contact angle measurement, and X‐ray photoelectron spectroscopy. Antifouling properties are evaluated by protein adsorption and bacterial adhesion experiments using Staphylococcus aureus in vitro. Higher O2 content in the mixture gas promotes hydrophilicity of the plasma‐treated PMMA, while a hydrophobic surface forms at higher CF4 content. Modifying PMMA improves antifouling performance regardless of the O2/CF4 volume ratio, and this improvement increases with rising CF4 content in O2/CF4 plasma working gas. Functional groups CO and CF are detected in O2/CF4 plasma‐treated PMMA surface and the ratio of CO to CF can be controlled by the O2/CF4 volume ratio in the plasma working gas.

show abstract

Comparison between AlGaN surfaces etched by carbon tetrafluoride and argon plasmas: Effect of the fluorine impurities incorporated in the surface

Cited by 12 publications

References 41 publications

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Characteristics of N₂ and O₂ Plasma‐Induced Damages on AlGaN Thin Film Surfaces

Plasma treatment of polymethyl methacrylate to improve surface hydrophilicity and antifouling performance

Contact Info

Product

Resources

About

Comparison between AlGaN surfaces etched by carbon tetrafluoride and argon plasmas: Effect of the fluorine impurities incorporated in the surface

Cited by 12 publications

References 41 publications

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Characteristics of N2 and O2 Plasma‐Induced Damages on AlGaN Thin Film Surfaces

Plasma treatment of polymethyl methacrylate to improve surface hydrophilicity and antifouling performance

Contact Info

Product

Resources

About

Characteristics of N₂ and O₂ Plasma‐Induced Damages on AlGaN Thin Film Surfaces